Systemic vasculitis in rheumatoid arthritis shows similarities to polyarteritis nodosa and may require equally aggressive therapy. Forty-five patients with systemic rheumatoid vasculitis were studied during treatment with either cyclophosphamide plus methylprednisolone given by intermittent bolus intravenous injection (21 patients) or a variety of other more conventional drug regimens (24 patients). In this open study, the intravenous treatment group had more severe initial disease, a higher incidence of neuropathy, and more frequent evidence of necrotizing arteritis on biopsy than the other treatment group. Despite this, intravenous cyclophosphamide plus methylprednisolone resulted in more frequent healing of vasculitic lesions including leg ulcers and neuropathy, a lower incidence of relapse, fewer serious complications, and a lower mortality than did other treatments. Toxic effects were similar in both study groups. Intravenous cyclophosphamide plus methylprednisolone is a useful early treatment for systemic rheumatoid vasculitis.